An estimated 40,000-45,000 Americans live in Haiti, and the U.S. Embassy had no confirmed reports of deaths among its citizens. All but one American employed by the embassy have been accounted for, State Department officials said.

Even relatively wealthy neighborhoods were devastated.

An AP videographer saw a wrecked hospital where people screamed for help in Petionville, a hillside district that is home to many diplomats and wealthy Haitians as well as the poor.

At a destroyed four-story apartment building, a girl of about 16 stood atop a car, trying to see inside while several men pulled at a foot sticking from rubble. She said her family was inside.

"A school near here collapsed totally," Petionville resident Ken Michel said after surveying the damage. "We don't know if there were any children inside." He said many seemingly sturdy homes nearby were split apart.

The U.N.'s 9,000 peacekeepers in Haiti, many of whom are from Brazil, were distracted from aid efforts by their own tragedy: Many spent the night hunting for survivors in the ruins of their headquarters.

"It would appear that everyone who was in the building, including my friend Hedi Annabi, the United Nations' secretary-general's special envoy, and everyone with him and around him, are dead," French Foreign Minister Bernard Kouchner said on RTL radio.

But U.N. peacekeeping chief Alain Le Roy would not confirm that Annabi was dead, saying he was among more than 100 people missing in its wrecked headquarters. He said only about 10 people had been pulled out, many of them badly injured. Fewer than five bodies had been removed, he said.

Brazil's army said at least 11 of its peacekeepers were killed, while Jordan's official news agency said three of its peacekeepers were killed. A state newspaper in China said eight Chinese peacekeepers were known dead and 10 were missing - though officials later said the information was not confirmed.

The quake struck at 4:53 p.m., centered 10 miles (15 kilometers) west of Port-au-Prince at a depth of only 5 miles (8 kilometers), the U.S. Geological Survey said. USGS geophysicist Kristin Marano called it the strongest earthquake since 1770 in what is now Haiti.

Video obtained by the AP showed a huge dust cloud rising over Port-au-Prince shortly after the quake as buildings collapsed.

Most Haitians are desperately poor, and after years of political instability the country has no real construction standards. In November 2008, following the collapse of a school in Petionville, the mayor of Port-au-Prince estimated about 60 percent of buildings were shoddily built and unsafe normally.

The quake was felt in the Dominican Republic, which shares the island of Hispaniola with Haiti, and in eastern Cuba, but no major damage was reported in either place.

With electricity out in many places and phone service erratic, it was nearly impossible for Haitian or foreign officials to get full details of the devastation.

"Everybody is just totally, totally freaked out and shaken," said Henry Bahn, a U.S. Department of Agriculture official in Port-au-Prince. "The sky is just gray with dust."